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					                                                                                                   PB Works


PB Works e-portfolio
Optimizing Photographs using Paintshop Pro 9

      Digital camera resolution is rated in
megapixels. Consumer class digital cameras
purchased in 2002-05 typically were rated
at 3.1 megapixels while most cameras now
are 12 megapixels. Consumers have been
confused over the megapixel rating in that
they assume that the higher the megapixel
rating the better quality photographs that
the camera can produce. Actually, a higher
megapixel rating only allows the user to
produce larger sized “photographic prints” without losing print quality. A wallet size photo taken
with a 3.1 megapixel or a 12 megapixel camera will be identical quality in final printed form. How-
ever, there is a huge difference in digital file sizes between the two photographs.

       This information can be stated in a different way. A pixel is short for picture element and it
holds data (position and color data - Red, Green and Blue) to display miniscule points of the image.
When many thousands of pixels are viewed together the image is formed. A 3.1 megapixel camera
will capture an image that is 2,048 pixels wide and 1,536 pixels in height (2048 x 1536 = 3,145,728
/ 1,000,000 = 3.1 megapixels) while a 12 megapixel camera will capture an image that is 4,000 pixels
wide and 3,000 pixels in height (4,000 x 3,000 = 12,000,000 / 1,000,000 = 12 megapixels).

      Digital cameras may “capture” images up to 300 pixels per inch (which is different than dots
per inch that is used with printing devices). A 3.1 megapixel camera will allow a quality photograph
to be printed up to dimensions of 5" x 7" and will have an average file size of 1 megabyte. A 12
megapixel camera will allow a photograph to be printed that is 9" x 14" and will have an average file
size of 2.5 megabytes. Settings on the camera allow the user to take photographs that are less than
300 pixels per inch and this can also be accomplished through using graphic editing software such as
Paintshop Pro to alter image files.

       The medium in which the photograph is to be displayed must be carefully considered. At least
150 pixels per inch is required for printing photographs but 72 pixels per inch is the maximum qual-
ity that will display on a computer monitor. Photographs displayed on web pages are frequently no
larger than 2"x 3". Using high quality images of 300 pixels per inch with 9" x 14" dimensions and
file sizes of 2.5 megabyte for web publishing is a tremendous waste of computing resources! The use
of large files will also effect the time it takes to upload files to the web server or wiki and the time it
takes to view pages over the Internet.

     Finally, a compression algorithm is used for .jpg image files in order to make the file size smaller.
This is done so that the file takes up less storage space and is able to be transferred over networks
more quickly. The degree of compression can adjusted allowing a trade-off between image quality
and file size. The file is compressed when it is saved and de-compressed when it is opened or read.

VISUAL ARTS 501A/601A                                                                                     1
PB Works


The .jpg format is said to be “lossy” compression because some information making up the image is
lost each time the image is altered and re-saved. A good practice is to maintain the original image of
the file and save altered images with different file names. The altered files are uploaded to the web
server or wiki. The original file can be used should a better quality image be required in future or if
an error is made when altering the copies. Images may be saved as .png files to prevent resolution
loss.

      It is a requirement that photographs be optimized for presentation in the PB Works e-port-
folio. Paintshop Pro 9 will be used to alter photographs before they are uploaded to the PB Works
portfolio (Adobe Fireworks and Photoshop are also well known graphics programs). Several online
image editing applications are available that may be used if Paintshop Pro is not readily available. As
an aside online social networking, sites such as Facebook, automatically optimize image files upon
upload based upon “average” settings and maximum file size limits.

      The following actions will be demonstrated to optimize images in Paintshop Pro 9:
      • crop the image to focus on the theme or object(s)
      • resize the image to the space allotted on the web page (e.g.: 200 pixels by 250 pixels)
      • change the colour depth (from 16.6 million to 2, 16, 256, 32K, or 64K)
      • apply compression to the image
      Performing these actions will reduce the average file size to below 200 kilobytes which is trans-
ferred relatively quickly over the Internet.

Determine the image size
                                                               It is assumed that images have been
                                                          transferred from the digital camera to a
                                                          storage device such as g: network drive or a
                                                          portable jump drive.

                                                          1. launch Paintshop Pro 9
                                                          2. open the image (YellowBird.jpg)

                                                                Note that the zoom control above
                                                          the viewing window provides information
                                                          regarding the portion of the image that
                                                          is displayed in the Paintshop Pro viewing
                                                          window (36% for this photograph).

Photo credit: James MacLean
                                                                Should the zoom be set to 100%
                                                          the user would need to use scroll bars to
                                                          view the entire photograph. The yellow
                                                          bird would fill roughly 1/4 of the viewing
                                                          window area! Perhaps you have received a
                                                          photograph through e-mail where you had
                                                          to scroll to see portions of the picture?

2                                                                                   VISUAL ARTS 501A/601A
                                                                                              PB Works


3. select Image - Image Informa-
    tion from the pull-down menu




This image was taken with an 8 megapixel camera. Note the image information that is provided:
    • the image size in pixels (1800 x 1591) and inches (10.000 x 8.839). This indicates that the
       camera was set to 3 megapixels when this photograph was taken.
    • the pixels per inch (ppi) of 180 (setting of camera when photo was taken - 150 pixels per
       inch will provide photograph quality when printing. This could have been set as high as
       300 ppi).
    • 617K file size on disk (compression was applied to the file by the camera)
    • 8,390K (8.39 meg) uncompressed data when file was re-opened in Paint Shop Pro
      This image that was transferred from the camera is too LARGE to use in the PB Works e-port-
folio. If it were to be used there would be lengthy wait times for the image to upload and to display
in the web browser. No difference in screen quality would be recognized between this file and one
that is much smaller. When done optimizing this photograph it will be well less than 200k in file
size!

VISUAL ARTS 501A/601A                                                                                   3
PB Works


Optimization Strategies
Crop the Image
     Determine the orientation of the photograph in the PB Works page. Will it be portrait or land-
scape? What will be it’s dimensions in pixels or inches? In the example, the bird will be cropped in
portrait orientation and the final image will be re-sized later to 200 pixels by 250 pixels. (To get the
bird cropped in the image, a larger area needed to be selected in the ratio of 400 by 500 which can
be reduced to 200 by 250 in the same aspect ratio. If the aspect ratio is not maintained the image of
the bird will skew. It will not look natural as it will appear too wide or too tall).
     1.    save the image with an alternate name e.g.: g:/YellowBird1.jpg
     2.    select the crop tool (found in the tool palette at the far left)
     3.    draw an outline around the bird
     4.    monitor the size at the top of the viewing window (it should be roughly 400 by 500 pixels)
     5.    key the values of 400 and 500 in the width and height input boxes
     6.    drag the selected area with the mouse so that it frames the bird exactly, as required
     7.    double click the selected area to crop it




4                                                                                  VISUAL ARTS 501A/601A
                                                                                              PB Works


     After cropping the image is shown at 100% size
and the yellow bird is framed as the dominate object
in the photograph.

     The largest portion of the image has been
cropped away. Check the image information to see
how this operation has changed the image file size.




                                                        The uncompressed file size has been reduced
                                                        in size from 8.39 megabytes to 586 kilobytes!

Resize the Image to 200 by 250 Pixels
      The photograph will be displayed in PB Works at 200 by 250 so the image is still twice as large
as it needs to be. After cropping, the second optimization strategy is to re-size the image.
      1. select the image pull-down menu
      2. select resize from the pull-down menu
      3. check the Lock aspect ratio box
      4. change the values of the width and height in
          the pixel dimension dialogue boxes
      5. choose Ok



      Check the file information after re-sizing the
image. What is the file’s size? (My file is showing
147K uncompressed; save the file. What is now the
size of the file On Disk? [the left number] Mine is
22K after saving!)




VISUAL ARTS 501A/601A                                                                                   5
PB Works


Decrease the Colour Depth
     A file size of 22K is excellent for use on a web site and most people would not take the time to
optimize the image further. However, there are occasions where large images may be required on the
web site and changing their colour depth and compression will greatly improve viewing performance.
1.   resave the file with a new name e.g.: g:/Yel-
     lowBird2.jpg (remember that resolution is
     lost every time a .jpg image is saved after a
     major change. This resolution can never be
     regained except by using the original version
     of the image)
2.   choose the image pull-down menu
3.   select Decrease colour depth
4.   choose 256 colours
5.   choose Optimized Octree and error diffusion
     in the resulting dialogue box
6.   save the file
7.   check the image information. What is the
     new file size? (Mine was 49K uncompressed
     and on disk remained at 22K) An explana-
     tion for this is that there were not many
     different colours in this photograph and it is
     relatively small in physical size. Therefore, file
     size did not decrease substantially.

Apply Compression to the Image
      The compression algorithm will allow .jpg
images to be split into like streams of “bytes”
when they are saved. This allows some data to be
removed in the saved file and reassembled when
the file is reopened. However, some resolution is
lost in the process. Higher file compression values
will result in more resolution loss.
       1. choose the File pull-down menu
       2. select Export from the pull-down menu
       3. choose JPEG Optimizer
       4. enter 33 for a compression value (select
            different values to observe how the im-
            age resolution changes)
       5. choose OK
       6. save the compressed image with a new
            name e.g.: g:/YellowBird3.jpg
       7. check the image information to deter-
            mine the new file size.

6                                                                                VISUAL ARTS 501A/601A
                                                                                                  PB Works


      The compressed file value of my image remained at 149K but the “On Disk file” fell to 7K in
size! This file size is often used for “thumbnail images” that appear on web sites. They appear very
quickly as the web page loads.

      Compression may be applied through the use of a wizard. The wizard provides further func-
tionality of estimated download times for the file with various Internet connections and the option
of creating progressive .jpg files which start to display on a web page when it first starts opens at low
resolution and continues to load until the full image resolution is displayed.




      To save time cropping and re-sizing images to their display sizes in PB Works will likely be suf-
ficient for most photographs. Any file that is under 200K in size should not hinder performance of
the Wiki site or put undue pressure on the school network.




VISUAL ARTS 501A/601A                                                                                       7

				
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